This invention relates in general to firearms and deals more particularly with an improved chamber status indicator for a semi-automatic or auto-loading handgun, which has a barrel including a headspace extension hood, and a method for retrofitting such a handgun with a chamber status indicator.
The present invention is concerned with improvements in firearms and particularly semi-automatic or auto-loading pistols of the type having reciprocal breech closures. Such pistols, of conventional construction, fire in response to trigger pressure and automatically re-load and return to closed breech position ready to fire again. The user of such an auto-loading pistol cannot determine with certainty whether there is a round in the barrel chamber after the pistol has been fired, because the breech is in its closed position.
Heretofore various mechanical devices have been provided on such auto-loading pistols to indicate the presence of a round in the chamber. Such mechanical devices typically employ intricate mechanisms and often include some form of mechanical sensor for engaging a portion of a chambered cartridge and altering the position of an associated externally exposed indicator, thereby signaling the presence of a cartridge in the barrel chamber. However, the provision of such a mechanical device on a firearm usually add substantially to the cost of producing the gun. Further, if a mechanical chamber status indicating device becomes damaged it may falsely indicate a safe or unloaded chamber condition, which could lead to a disastrous result. Those devices which provide chamber status indication by the change of position of an indicator may require the gun user to rapidly recall the indicator position associated with a particular chamber condition, which introduces the possibility of human error.
A further approach to the problem has been to provide a sighting opening in the barrel which opens into the bore immediately forward of the cartridge chamber or into the cartridge chamber to allow direct viewing of a portion of a chambered cartridge. However, as far as can be determined, previous efforts to provide a satisfactory observation port in the barrel of a firearm have been unsuccessful. Another somewhat similar approach has been to provide a peep-notch at least partially defined by the bolt and opening through the bolt face to permit direct observation of a portion of the rim or base of a chambered cartridge. However, of the aforesaid approaches are invasive to critical parts of the firearm and tend to compromise the structural integrity of either or both the barrel and the bolt, which may cause cartridge jamming or improper cartridge extraction.
Accordingly, it is the general aim of the present invention to provide, in a semi-automatic or auto-loading handgun having a reciprocally movable breech closure and which includes an improved chamber status indicator which allows direct visual inspection of a portion of the breech when the breech closure is in its closed position. A further aim of the present invention is to provide a breech observation aperture in a firearm of the aforedescribed type without compromising the structural integrity of the firearm or significantly increasing the cost of producing it. Yet, another aim of the invention is to provide a method for retrofitting a firearm of the aforedescribed general type to provide the firearm with a breech observation aperture without jeopardizing the structural integrity of the firearm.
In accordance with the present invention, an improved auto-loading pistol has a frame and a slide which includes a forwardly facing bolt face and an upwardly and laterally outwardly open ejection port. The slide is supported on the frame for forward and rearward reciprocal movement between firing and retracted positions respectively corresponding to closed and open breech conditions. The pistol further includes a barrel having a rearwardly facing breechface, a bore defined by and extending through the barrel, a chamber at the rear of the bore and opening through the breechface, and a headspace extension hood projecting rearwardly from the breechface above the chamber. In the closed breech condition the headspace extension hood overlies headspace formed between the breechface and the bolt face. In accordance with the present invention, a chamber status indicating means is provided for enabling a user of the gun to determine whether a round of ammunition is chambered within the gun and comprises a rearwardly open first notch formed in the headspace extension hood and a forwardly open second notch formed in the slide. The first notch is exposed within the ejection port when the slide is in a closed breech or firing position and cooperates with the second notch to permit a user of the pistol to determine chamber status by direct observation while pointing the pistol down range.